1. [1] Recommendation ITU-T G.811 (1997), Timing characteristics of primary reference clocks [Electronic resource]. - Available at: https://www.itu.int/rec/T-RECG.811-199709-I/en.
2. [2] Recommendation ITU-T G.811.1 (2017), Timing characteristics of enhanced primary reference clocks [Electronic resource]. - Available at: https://www.itu.int/rec/TREC-G.811.1-201708-I/en.
3. [3] Recommendation ITU-T G.812 (2004), Timing requirements of slave clocks suitable for use as node clocks in synchronization networks [Electronic resource]. - Available at: https://www.itu.int/rec/T-RECG.812-200406-I/en.
4. [4] EN ISO/IEC 17025:2017 General requirements for the competence of testing and calibration laboratories. [Electronic resource]. - Available at: https://www.iso.org/ standard/66912.html
5. [5] EA-04/02. Evaluation of the Uncertainty of Measurement in Calibration. [Electronic resource]. - Available at: https://www.accredia.it/en/documento/ea-4-02-rev-03- evaluation-of-the-uncertainty-of-measurement-in-calibration/